1. Field of the Invention
The invention generally pertains to the field of measuring a planar surface and its edges. More particularly, the invention pertains to a method and apparatus for measuring base edge bevel angles and base flatness of a ski or snowboard for increased performance.
2. Description of Related Art
Down hill snow skis and snowboards are made from a wide variety of materials, including wood, fiberglass, plastics, resins, composites and the like. These materials generally are put into molds, then glued, heated and pressed together. The result is a ski or snowboard with a gliding surface (a base against the snow) that is parallel with the top of the ski. More specifically, the base is manufactured to be parallel to the binding plate area on top of the ski or snowboard.
The bases of snowboards and skis typically are made from a hard plastic material, such as Ultra-High-Molecular-Weight Polyethylene (UHMWPE or sometimes shortened to UHMW), also known as high-modulus polyethylene (HMPE) or high-performance polyethylene (HPPE). This dense, extremely durable, abrasion-resistant thermoplastic material has low friction properties, is easily repairable and openly accepts wax, in order to improve its gliding efficiency in a variety of snow conditions. UHMW ski and snowboard base materials generally are of two types, extruded or sintered, and grades vary slightly in their density and additives, but all are capable of absorbing wax and differ from regular UHMW, in that they are specially treated for bonding with epoxy resin. “P-tex”, “Isospeed”, and “Durasurf” are common brand names in the industry, and all are high quality parts, used by most major manufacturers. Examples of some known high performance ski base materials are disclosed in U.S. Pat. Nos. 5,189,130 and 5,069,976.
The bases of most modern down hill skis and snowboards also have two metal edges on the lower surface, which typically run the length of both lower edges of the ski to aid in griping the snow and turning. In order to obtain the benefits of using well-tuned skis, which generally is important to all skiers and riders, but particularly to proficient downhill skiers, racers and riders, the edges of the skis must be maintained in a smooth, sharp condition to provide top performance characteristics and consistent edge bite, especially on icy or hard snow surfaces. More particularly, the base must be planed or ground true or flat and both the side and bottom of the metal edges must be sharpened regularly. Beveling of the metal edges also is commonly performed, while sharpening. By beveling the edges, changes in the drag and turning characteristics of the ski or board can be greatly affected. This process of sharpening and beveling the edges to achieve specific performance characteristics generally is known as tuning the ski. Although waxing really is a separate art, waxing also can be considered part of ski tuning, particularly as applied to increased performance.
Ski-owners can tune their own skis, if suitable tools and the necessary skill for doing so are available, and many racers prefer to tune their skis and snowboards in their own shop or even in the field. Accordingly, a wide variety of devices have been developed for sharpening ski edges, which generally fall into two categories: manual sharpeners and motorized sharpeners. Many different types of manual or hand-held ski sharpening devices are known, but these generally produce variable results, particularly for those seeking top performance. Examples of a variety of known hand-held ski sharpening devices are disclosed in U.S. Pat. Nos. 4,721,020; 4,509,297; 4,280,378; 4,089,076; 4,060,013; 3,934,287; 3,899,942 and 3,875,825.
Manual sharpeners tend to include a file with a file holder to maintain file or cutting tool alignment. There are significant problems with such manual devices. Specifically, these units are hard to keep aligned, removal of metal is uneven and because of the size of the file teeth, the file generally needs to straddle both sides of the ski, leading to interference with the base material and uneven filing of the bottom edge. Another problem with manual sharpeners is their typical inability to adjust the angle on the file, leaving the user with right angles (a zero degree bevel) as the only choice, or at best a single choice of bevel angle. Because many of these manual sharpeners require a certain amount of skill and are difficult to use, they generally produce variable results.
The majority of motorized sharpeners are large floor or bench-type models, designed primarily for use in professional ski shops. Examples of known motorized ski sharpening devices are disclosed in U.S. Pat. Nos. 6,702,656; 5,136,816 and 4,679,356. While there is at least one small hand-held motorized unit disclosed in the art, it suffers from difficulties in keeping the sanding disc at a proper angle, since the motor, motor shaft and sanding disc are held parallel to the ski edge during use. The weight of the motor that is not supported in this configuration makes balancing the system difficult. A further problem with this design is the tendency for the sanding disc to “run-away” from the user if not held tightly.
Professional ski shops typically are considered the best place to take skis for sharpening the ski edges. These shops can afford the large motorized sharpening machines that hold the skis firmly in place and quickly sharpen the whole ski. This is conventionally done by skilled personnel carrying out ski sharpening services in association with the sale of skis and ancillary skiing equipment. However, the time and cost of taking the skis to a professional shop discourages many people from doing such sharpening as often as it should be done for optimal performance. Moreover, if the machine is not properly calibrated, or if the operator is inexperienced or unskilled, even the best automated equipment cannot tune a ski properly for high performance.
Among other important observations, Applicant has discovered that, if the base of the ski is not planed true prior to setting base edge bevels, the left and right edges may end up being asymmetric. The base is the one surface from which most measurements are taken and it must be flat, relative to the binding plate/area. To Applicant's knowledge, the prior art fails to recognize, teach or suggest this problem and the currently available equipment does not adequately resolve the problem. Applicant has therefore created an improved system for accurately measuring base flatness and edge bevel angles, which overcomes the problems associated with the prior art. This system also helps the service shop technician or home technician make adjustment in the use of his or her own tools, techniques, and methods to improve the accuracy of tuning results.